The move to alternative energy sources for electric devices and electric vehicles has increased the demand for better battery technology. Batteries typically store energy in a particular volume, where the density of the energy is referred to as the volumetric energy density. Increasing the volumetric energy density of batteries typically involves making thick electrodes. This decreases total volume of inactive materials such as separator and current collectors, thereby increasing the volumetric energy density.
However, thick electrodes undergo mechanical stresses. Sources of the mechanical stresses come from stack pressure that ensures the adhesion between the electrodes and the current collectors. Another source of mechanical stress lies in internal strain resulted from the expansion and contraction of the battery electrode as the lithium ions intercalate and de-intercalate into and out of the electrode material during charging and discharging. This results in severe fading of long-term cycling capacity in thick battery electrodes.
In addition, severe electrolyte depletion with increasing thickness occurs due to long lithium ion (Li-ion) diffusion lengths and poor Li-ion conductivity in complex microstructure electrodes. This results in less material utilization, reducing the volumetric energy density.